Self actuated mechanism for braking a driven member upon discontinuation of drive thereto

ABSTRACT

A mechanism adaptable for connection between a drive and rotatable shaft to provide a driving connection therebetween when mechanical power flows from the drive to the shaft, the mechanism being operable to produce a self-actuating braking force on the shaft when the power flow is interrupted thereby preventing extended free-wheeling of the shaft.

United States Patent Zurek et al. [4 1 Mar. 27, 1973 [54] SELF-ACTUATEDMECHANISM FOR [56] References Cited BRAKING A DRIVEN MEMBER UPON UNITEDSTATES PATENTS DISCONTINUATION OF DRIVE 1 532 877 4/1925 B k 192/8 R ucTHERETO 1,863,556 6/1932 Cottrell ..192/15 [75] Inventors; James W,Zurek, Lombard; D id 3,194,367 7/1965 Winter ..l92/l6 A. Fulghum, LaGrange, both of 111. Primary ExaminerCharles J. Myhre [73] Assignee:International Harvester Company, Assistant Examiner Randa1] HealdChlcago, Attorney-Floyd B. Harman [22] Filed: Apr. 13, 1971 [57]ABSTRACT 21 A LN 133641 1 PP O A mechanism adaptable for connectionbetween a drive and rotatable shaft to provide a driving connec- [52]US. Cl. ..192/8 R, 192/16 tion therebetween when mechanical power flowsfrom [51] Int. Cl ..F16d 67/00 h dr to the h f th mechani m beingoperable [58] Field of Search ..192/8, 15, 16, 64, 36 to P m aself-actuating braking force on the shaft when the power flow isinterrupted thereby preventing extended free-wheeling of the shaft.

13 Claims, 6 Drawing Figures 57 n w" 1" 4a 4 5 if" 5O v .w 40. 38 4 j 1f r l 35 IO 1? 636, I |8 18 C l '1 I9 1 as n 14 {w 13 ;H II 1 2 22 i c::n 32 I It; 23

. I I I :lm 29 I 27 5| I I 2a a H i i w I a: I t n PATENTEUHARZYIHTS 72242 SHEET 1 OF 3 IN VE N TORS JAMES W. ZURE K DAVID A FULGHUM W AMPATENTEDHARZYISYS 3 722,642

SHEET 2 OF 3 ulllllllw H IN VE N TORS JA MES W. ZURE K DAVID A. FULGHUMBYdMHaZ ATTX PATENTEDHARZ? ma SHEET 3 OF 3 IN VEN TORS JA MES w. ZUREKDj l DA. FULG HUM ATT'Y.

SELF-ACTUATED MECHANISM FOR BRAKING A DRIVEN MEMBER UPON DISCONTINUATIONOF DRIVE THERETO BACKGROUND OF THE INVENTION Oftentimes it is desirableto provide a braking mechanism on rotating equipment to expend thekinetic energy stored in driven members and thereby prevent extendedfree-wheeling of those members after a driving source has beendisconnected. Manually operated braking devices can, of course, beprovided with the attendant disadvantage that they are dependent on anovert act of an operator. It is apparent that in certain situations,such as the driving of rotary cut ters in lawn mowers, choppers or otherforms of equipment having rotary members more or less accessible to anoperator, manually operable braking devices to stop such rotary memberscould be employed with an included disadvantage that the operator mustcontinually remember to engage and disengage the brake duringoperations. Often such devices fall into disuse.

Others have employed overrunning clutches which do not provide a brakingaction on the rotating members but rather produce an audible sound whenthe driving source is disconnected which may alert the operator that therotary member is still in motion.

The general object of the instant invention is to provide a brakingmechanism or device operatively connectable to a rotatable memberwherein a self-actuating braking force is effected on those members toprevent their extended free-wheeling motion.

Another object of the invention is to provide that the braking device beeffective to couple power transmission from a driving source to therotary members and be operative to produce a self-actuating brakingaction on those members when the transmitted power is interrupted.

A more specific object of the foregoing is that the invention utilizethe momentum of the rotary members while in free-wheeling motion toactuate the mechanism and provide forces to effect the braking action.

Still another object of the invention is to provide that the brakingmechanism be adaptable for use in a plurality of positions andsubstantially independent of gravitational forceS.

A general object of the embodiments of the invention herein described isto provide the mechanism be adaptable to mount on a drive shaft carryingthe rotatable members and include means for receiving power from thedriving source.

Another object of the invention as delineated in the embodiments is toprovide a driving connection to the shaft when mechanical power flow isdelivered thereto in a certain direction and produce braking forces tothe shaft when that flow is reversed.

Still another object of the invention is to provide that an element ofthe mechanism having a braking surface engageable with another surfaceto efiect a braking action whereat the angular relationship of thissurface during engagement produces a wedging action thereat.

A more specific object of the foregoing is to provide that the elementof the mechanism having the braking surface and the other surface moveinto engagement during braking operations wherein the momentum of therotary members in free-wheeling motion provides forces effecting suchmovement.

A still further object of one of the embodiments is to provide amechanism in which the drive shaft is substantially axially staticduring both driving and braking operations.

A more specific object of the invention is to provide that a supportingstructure journalling the drive shaft 1 have braking surfaces disposedin angular interacting relation to the braking surface on the mechanism.

Other objects and features of the present invention will become morefully apparent in view of the following detailed description taken inconjunction with the accompanying drawings illustrating embodimentsincorporating the inventive concepts hereinafter disclosed.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational viewpartially in section of a first embodiment of a drive-brake mechanismincorporating the invention as applied to a simple power transferringdevice and showing the same in a driving position;

FIG. 2 is an enlarged exploded pictorial view of the drive transfermechanism shown in the first embodiment;

FIG. 3 is a partial sectional view of FIG. 1 showing the mechanism in abraking position;

FIG. 4 is an enlarged fragmentary sectional view of the interactingbraking surfaces of the first embodiment illustrating their angularrelationship;

FIG. 5 is an elevational view partially in section of a secondembodiment of a drive-brake mechanism and showing the same in a drivingposition; and

FIG. 6 is a partial sectional view of the mechanism of FIG. 5 taken atline 66 of FIG. 5.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The standard 12 has a centralbore 19 in which a shaft 20 is joumalled and rotatably supported byupper and lower bearings 21 and 22 respectively. The mechanism 10 isshown arranged in a vertical orientation for illustration purposes only.It is to be understood that the mechanism may be utilized in otherpositions than shown and references to an upper or lower disposition.

of parts is used merely for convenience in describing its structure.

The lower end of the shaft 20 protrudes from the sleeve and has a hub 23secured thereto by a key 24 and bolt 26 threaded into bore 27 as shown.The hub 23 has a pair of diametrically disposed ears 28 and 29 therebyin which bolt assemblies 32 secure thereto a member 33 which may be acutting blade of a mower.

A wear washer 34 is disposed between the hub 23 and lower edge of sleeve12.

The upper end of the central bore 19 has a widened portion 35 forming ashoulder which receives a bearing 36 which rotatably supports a washerwear member 37 held in position about the shaft by a nut 38 threadedlysecured on a threaded part of the shaft 20 disposed within the widenedportion in the position shown. It can be appreciated that thisarrangement will prevent substantial axial displacement of the shaft 20within the standard 12 as the shaft is constrained to rotate about acommon and coincidental axis designated XX of the shaft 20 and centralbore 19. Adjacent the widened portion 35 the bore 19 widens at 31 andthen flares outwardly to define the braking surface 40 which isconically shaped and symmetrically disposed about the axiS XX. At theupper end of the standard 12 the bore 19 has a still wider portion 41into which is nested a dust seal 42.

As best seen in FIG. 2 the shaft 20 includes a power drive shank portion43 which extends outwardly and upwardly from the nut 38. A continuouslyhelical land or rib 44 is spirally formed about said shank 43 andextends from the nut 38 to a shoulder 45 from which extends adiametrically smaller splined portion 46. A groove 47 is provided abovethe splined portion 46 and that end of the shaft 19, as shown.

A drive member 48 which also serves as a brake member is disposed on theshank portion 43 Of the shaft 20. The member 48 haS a bore with a spiralgroove 49 and interthreadedly tits on rib 44. The lower end of themember 48 has beveled or conical braking surface '50 which is angled tocomplementally mate with the braking surface 40 of the support sleeve12. In operation when member 48 is rotated relative to the shaft 20 in adirection as indicated by arrow A FIG. 3, the member 48 will ride on therib 44 and move outwardly, that is upwardly, toward the splined portion46 of the shaft 20. Conversely when relative rotation of the member 48in the opposite direction occurs it will move in an axial inward ordownward direction such, that surfaces 40 and 50 engage. At the upperend of the member 48 the diameter thereof is reduced to provide ashoulder surface 51 onto which a sheave 52 can be affixed to the member48 by such means as welding as indicated at 53. It is apparent that asprocket, coupling mechanism or other drive devices could be easilyadapted to siMilarly mount the member 48. A pair of diametricallydisposed driving lugs 54 and 55 are provided on this reduced end of themember 48; and each of the lugs (54, 55) are of sector form definingspaces 56 therebetween. Drive hub stop means 57 have a splined innerbore 'complementally matingly mounted onto the splined portiOn 46 of theShaft 20 and thereby constrained to rotate therewith. A locking ring 58is fitted into the groove 47 to hold the hub 57 captive on the shaft 20between the shoulder 45 and the ring 58 whereby axial movement of thehub 57 is prevented. The inner end of the hub 57 has a pair ofdiametrically disposed engaging jaw clutch lugs 59 and 60 with spaces 67therebetween. The spaces 67 have sufficient dimension and are disposedrelative to the lugs (54, 55) and spaces (56, 60) to provide for thenecessary rotary travel of the member 48 about the shank to effect axialdisplacement to and from braking engagement with the sleeve 12. FIG. 3(which illustrates the mechanism 10 in braking position) shows that agap 62 is provided between the member 48 and the hub 57. The hub 57should be arranged on the splined shaft such that the driving lugs 54and 55 of the member 48 drivingly engage the lugs 59 and 60 of thedriving hub 57, just before the gap 62 closes. This prevents substantialoutward axial thrust on the hub 57 by the member 48 when it is beingdriven in by the sheave 52.

EMBODINIENT OF FIGS. 5 AND 6 Attention iS now directed to the secondembodiment shown in FIGS. 5 and 6, which depicts another drivebrakemechanism which is operatively similar to the mechanism 10 of the firstembodiment, but has certain other novel features hereinafter described.

The mechanism 70 comprises a sleeve 71 having flanges 72 and 73 whichhave holes 74 and 75 for mounting the sleeve 71 by bolt assemblies asshown to a housing 76 of a chopplng mechanism, such as a forage chopperas suggested in FIG. 5. The standard 71 has a central bore 77 into whicha shaft 78 is disposed and joumalled therein by bearings 79 and 80. Theinner end of the shaft 78 extends from that end of the sleeve 71 and hasa threaded bore 81. A hub 82 is secured to the shaft by key 83 and bolt84 with a wear washer 85 providing necessary clearance. The hub 82 haslugs 86 and 87 each with holes for mounting to an end plate 88 of arotatable element such as a forage chopping rotor designated 89 by meansof bolt assemblies 90.

Toward the other end of the sleeve 71 the central bore 77 has a widenedportion 91 defining a shoulder against which is placed a bearing 92. Asnap ring 93 rides on the bearing 92 and is simultaneously disposed inaligned grooves 94 and 95 disposed in the shaft 78 and the wall of thesleeve at the widened portion 91 of the bore 77 respectively to therebyretain the shaft 78 in the position and prevent axial movement thereof.Adjacent the portion 91 the bore 71 flares outwardly and is shaped toform an internal conical braking surface 96. Outwardly from the brakingsurface 96 the bore 71 is enlarged diametrically and presents acircumferential surface 97 and a radial surface 98. A groove 99interrupts surface 97 adjacent the surface 98.

The shaft 78 comprises ascrew portion 100 which extends from the snapring groove 94 outwardly toward the outer end thereof. This portion 100has a continuous helical land or thread 101 disposed thereabout asshown. The shaft 78 extends outwardly beyond the sleeve 71 and thereathas a threaded portion 102 which is diametrically smaller than the screwportion to provide a shoulder surface 103.

A drive-braking member 104 which comprises a cylindrical body with alower conical surface 105 and an upper shoulder portion 106 has aninternal bore 107. A spiral groove or thread 103 is formed in bore 107and is dimensioned to rotatably fit and screw on and off the screwportion 100 of the shaft 78 by threading on and off thread 101 to effectan axial movement of the member 104 relative to the shaft 78 uponrelative rotary motion between the shaft 78 and member 104.

A sheave 109 and dust cover 110 are secured to the member 104 againstshoulder portion 106. A dust seal 111 is provided between the body ofthe member 104 and wall surface 97 of the sleeve 71. A stop washer l 12is disposed on the shoulder 103 of the shaft 78 to restrict (outward)upward axial travel of the member 104 upon relative rotation to theshaft 78. The washer 112 is held in position by nut 113 threadedlyfitted on the end portion of the shaft. FIG. 5 shows that a gap 1 14 hasbeen provided between the washer 112 and the adjacent end of the member104 when the surfaces 96 and 105 are in engagement. It can beappreciated that when relative rotary motion between the member 104 andthe shaft 78 (as indicated by arrow A) occurs the member 104 willaxially move (outwardly) upwardly to close the gap 114 and abut thewasher 112, and thus the member 104 can move axially from brakingcontact with the standard 71 to a drivinG relation with shaft 78 uponbeing stopped by the washer l 12.

The member 104 also has a notch 115 (FIG. 6) extendlng axially along itsbody from the beveled end thereof. A drag spring or reaction ring 116has an inwardly projecting hole or leg 117 entered into the notch 115and an annular portion 116a compressed within groove 99 in continualfrictional engagement with the sleeve 71. The drag rinG 116 is formed ofspring steel and of such a diameter that it must be compressed to fitinto the groove 99 and thus in constant pressure engagement with thesleeve 71. This provides a frictional retarding force on the member 104manifest as a counter torque being generally opposite in direction to adriving torque applied to drive the member 104 in the diRectionindicated by the arrow B.

OPERATION OF EMBODIMENT OF FIGS. 1-4

The operation of the first embodiment is as follows: First consider themechanism 10 being mounted on the mower housing 11 and in the brakingmode as shown in FIG. 3, and a drive belt as indicated at 15 transmitsdriving torque from a suitable power source (not shown) to the sheave 52and the member 48 causing them to rotate relative to the shaft asindicated by the arrow A.

As this occurs action between the land 44 on the shaft and the groove 47of the member 48 provides axial movement of member 48 such that thebraking surfaces 40 and 50 disengage. The axial movement continues untilthe lugs 54 and 55 of the member 48 drivingly engage the lugs 59 and 60of the driving hub 57 wherein the relative rotation movement between themember 48 and shaft 20 ceases and they both begin to rotate togetherwith the member 48 driving the shaft 20 through the hub 57 whereby thecutting element 33 is rotated at a selected speed. It should be notedthat the entire driving torque is tangentially applied to the shaft 20by the peculiar engagement of the member 48 and driving hub 57. As longas the belt 15 is driven at the same rate the member 48 remains indriving relation to the hub 57 as hereinbefore described; this isbecause some torque is continually required to be delivered to themechanism to maintain the selected speed of the cutting element 33.

When the driving torque delivered from the source is interrupted such asthrough the loosening of the belt 15 (through a suitable idlerarrangement not shown), the momentum of the moving cutter element 33 nowsupplies torque to the hub 57 to drive the sheave 52 and the member 48.Torque must be supplied to drive the member 48 due to its resistance, tostay in motion caused by actions such as a wind resistance on the sheaveand frictionAl resistance of the dust seal 4 contacting the member 48producing a retarding or counter torque thereon. The cutting element 33secured to the hub 57 now provides the driving torque. It can beappreciated that in order for the hub 57 to drive the member 48 theremust be relative counter rotation between the member 48 and shaft 20.When this occurs the member 48 counterrotates relative to the shaft 20wherein it moves axially inward or downwardly toward the standard 12 dueto the action of the land 44 and groove 49. This inward movementcontinues until the braking surfaces 40 and 50 engage. The engagement ofthe braking surfaces 40 and 50 increase the counter-torque applied tothe member 48 which in turn increases the inward axial thrust due to theincreased lag on retardation of the member 48 relative to the rotatingshaft 20 and therefore, action of the mechanism 10 is self-actuating andself-generating.

OPERATION OF EMBODIMENT OF FIGS. 5 AND 6 The operation of the secondembodiment is essentially similar to that of the first. The drive-brakemember 104 rotates relative to the shaft 78 when the sheave 109 isdriven by a power source. This produces an initial relative rotationalmovement between the shaft 78 and the member 104 which causes the member78 to move axially (outward) upwardly through the action of the land 101and groove 108 on the member 104 and shaft 78 respectively. The member104 continues to move axially until restrained by the stop washer 112whereat the braking surfaces 105 and 96 of the member 104 and standard71 respectively are disengaged and the member 104 is in driving relationto the shaft 78. In this embodiment the drag ring 116 provides aninitiating counter torque on the member 104 which effectscounter-rotation of the member 104 when the driving torque applled tothe sheave 109 is interrupted. At this time the momentum of the rotor 89is now the driving force on the shaft 78 and the countertorque producedby the ring 1 16 along with the shaft 78 being in driving relation tothe member 104 cause a counter rotation of the member 104 on the shaft78 producing an attendant inward axial movement of the member 104 untilthe braking surfaces 105 and 96 engage. When this occurs the brakinGaction becomes self-generating because the counter-torque is initiallyincreased which in turn increases the inward thrust of the member 104thereby forcing the braking surfaces more tightly together.

It will be appreciated that the embodiments of the invention chosen forthe purposes of illustration and description herein are preferred basedupon require ments for achieving the objects of the invention anddeveloping the utility thereof in the most desirable manner, due regardbeing had to existing factors of economy, simplicity of design andconStruction, production method and the improvements sought to beeffected. It will be understood, that the particular structure andfunctional aspect emphasized herein are not intended to exclude butrather to suggest such other modifications and adaptations as fallwithin the spirit and scope of the invention.

What is claimed is:

1. An implement having a cutter, a drive-brake mechanism for driving andbraking said cutter auto.-

matically shiftable between drive and brake conditions in response tothe direction from which drive torque is delivered thereto comprising:

support means 12, 71 having a first braking surface 40, 96 thereon;

torque transfer means 20, 78 journalled on said support means;

torque transmitting means 52, 109 coupled by coupling means to saidtorque transfer means, said torque transmitting means having means 48,104 rotatably drivable from a source of driving torque;

said torque transmitting means including a second braking surface 50,105 disposed for engagement with said first braking surface;

a normally driven energy-storing structure such as a cutter 33, 88positively connected with said torque transfer means and driven therebyattendant to said torque transfer means being driven by said torquetransmitting means in driving relation to said torque transfer meansupon termination of drive thereto from said source;

shifting means 44, 49 100, 108 responsive to the direction from whichdriving torque is transmitted between said torque transfer means andsaid torque transmitting means, operative to move said torquetransmitting means to a position disengaging said braking surfaces andestablishing a driving relation with said torque transfer means uponsaid torque transmitting means being driven by the source of drivingtorque and operative to move the second braking surface of said torquetransmitting means into engagement with said first braking surface uponsaid torque transfer means being driven by said energy storingstructure.

2. The invention as recited in claim 1 wherein said shifting meanseffects axial movement of said torque transmitting means between brakeengaged and disengaged positions.

3. The invention as recited in claim 2 wherein said braking surfaces arein the form of cone brakes.

4. The invention as recited in claim 3 wherein said shifting meanscomprises interthreaded threads on said torque transmitting means andsaid torque transfer means to produce counter axial displacement of saidtorque transmitting and torque transfer means to effect a driving ofsaid torque transfer means by axial displacement of the torquetransmitting means in one direction and a braking of said torquetransfer means through axial displacement of the torque transmittingmeans in the other direction such that said braking surfaces engage.

5. The Invention as recited in claim 4 wherein drag means is operativeagainst the torque transmitting means to load the same to initiallyinduce saidaxial displacement thereof to effect engagement of saidbraking surfaces.

6. In an agricultural implement of the type having a housing mounting arotor driven from an associated source, the improvement comprising: adrive-brake mechanism comprising:

a sleeve mounted on said housing and having a braking surface thereon;

a shaft journalled through said sleeve and comprising a spiral land;

a rotor mounted on the shaft;

an input member rotatably drivable by said source, said member having aspirally grooved bore threaded on the land wherein reverse relativerotary motions between said input member and said shaft effectcorresponding axial displacements of said input member on said shaft,and said input member including a braking surface disposed adjacent saidbraking surface of said sleeve for engagernent therewith when the rotoroverruns the driving source.

7. The invention as recited in claim 6 wherein said drive-brakemechanism includes drag means operative to hold said input memberagainst entrainment by said rotor when said shaft is in driving relationto said input member.

8. The invention as recited in claim 7 wherein said input membercomprises an annular drag surface, and said drag means comprisesstationary sphincteral spring means anchored to the sleeve and wrappedabout said surface to provide a torque load thereon.

9. For a cutter including a casing, a drive-brake mechanismautomatically shiftable within a range between drive and brake positionsin response to the direction from which driving torque is deliveredthereto comprising;

a. three coaxially arranged bodies including;

b. a first body connected to a source of driving torque; first c. asecond body coupled by coupling means at one extreme of said range tosaid first body and functioning as a guide axis therefonsaid second bodyprovided with output means;

d. a third body held against rotary entrainment by said casing saidsecond body supported by said third body and said first and third bodiesprovided with confronting braking surfaces, said confronting brakingsurfaces arranged to engage at the other extremity of said range;

. and means for relatively shifting said first and third bodies axiallyto engaged position of the braking surface to stop rotation of saidfirst and second bodies upon discontinuance of delivery of drivingtorque to said first body, and to disengaged position of the brakingsurfaces to'effect drive from the first to the second body inconsequence of driving torque being delivered to the first body 10. Theinvention according to claim 9 and said first body comprising a rotarymember, said second body comprises a shaft and the third body comprisesa sleeve providing a journal for the shaft.

11. The invention as set forth in claim 1 wherein said coupling meanscomprise lugsextending axially from both said torque transfer means andsaid torque trans mitting means, said lugs having axially alignedconfronting surfaces that engage to transmitrotary motion from saidtorque transfer means to said torque trans mitting means.

12. The'invention as set forth in claim 6, wherein there are couplingmeans between said input members and said shaft, said coupling meanscomprise lugs extending axially from both said input member and saidshaft, said lugs having axially aligned confronting surfaces that engageto transmit rotary motion from said input member to said shaft.

2. The invention as recited in claim 1 wherein said shifting meanseffects axial movement of said torque transmitting means between brakeengaged and disengaged positions.
 3. The invention as recited in claim 2wherein said braking surfaces are in the form of cone brakes.
 4. Theinvention as recited in claim 3 wherein said shifting means comprisesinterthreaded threads on said torque transmitting means and said torquetransfer means to produce counter axial displacement of said torquetransmitting and torque transfer means to effect a driving of saidtorque transfer means by axial displacement of the torque transmittingmeans in one direction and a braking of said torque transfer meansthrough axial displacement of the torque transmitting means in the otherdirection such that said braking surfaces engage.
 5. The Invention asrecited in claim 4 wherein drag means is operative against the torquetransmitting means to load the same to initially induce said axialdisplacement thereof to effect engagement of said braking surfaces. 6.In an agricultural implement of the type having a housing mounting arotor driven from an associated source, the improvement comprising: adrive-brake mechanism comprising: a sleeve mounted on said housing andhaving a braking surface thereon; a shaft journalled through said sleeveand comprising a spiral land; a rotor mounted on the shaft; an inputmember rotatably drivable by said source, said member having a spirallygrooved bore threaded on the land wherein reverse relative rotarymotions between said input member and said shaft effect correspondingaxial displacements of said input member on said shaft, and said inputmember including a braking surface disposed adjacent said brakingsurface of said sleeve for engagement therewith when the rotor overrunsthe driving source.
 7. The invention as recited in claim 6 wherein saiddrive-brake mechanism includes drag means operative to hold said inputmember against entrainment by said rotor when said shaft is in drivingrelation to said input member.
 8. The invention as reciteD in claim 7wherein said input member comprises an annular drag surface, and saiddrag means comprises stationary sphincteral spring means anchored to thesleeve and wrapped about said surface to provide a torque load thereon.9. For a cutter including a casing, a drive-brake mechanismautomatically shiftable within a range between drive and brake positionsin response to the direction from which driving torque is deliveredthereto comprising; a. three coaxially arranged bodies including; b. afirst body connected to a source of driving torque; first c. a secondbody coupled by coupling means at one extreme of said range to saidfirst body and functioning as a guide axis therefor, said second bodyprovided with output means; d. a third body held against rotaryentrainment by said casing said second body supported by said third bodyand said first and third bodies provided with confronting brakingsurfaces, said confronting braking surfaces arranged to engage at theother extremity of said range; e. and means for relatively shifting saidfirst and third bodies axially to engaged position of the brakingsurface to stop rotation of said first and second bodies upondiscontinuance of delivery of driving torque to said first body, and todisengaged position of the braking surfaces to effect drive from thefirst to the second body in consequence of driving torque beingdelivered to the first body.
 10. The invention according to claim 9 andsaid first body comprising a rotary member, said second body comprises ashaft and the third body comprises a sleeve providing a journal for theshaft.
 11. The invention as set forth in claim 1 wherein said couplingmeans comprise lugs extending axially from both said torque transfermeans and said torque transmitting means, said lugs having axiallyaligned confronting surfaces that engage to transmit rotary motion fromsaid torque transfer means to said torque transmitting means.
 12. Theinvention as set forth in claim 6, wherein there are coupling meansbetween said input members and said shaft, said coupling means compriselugs extending axially from both said input member and said shaft, saidlugs having axially aligned confronting surfaces that engage to transmitrotary motion from said input member to said shaft.
 13. The invention asset forth in claim 9 wherein said coupling means comprise lugs extendingaxially from both said first and second bodies, said lugs having axiallyaligned confronting surfaces that engage to transmit rotary motion fromsaid first body to said second body.